Proof of purchase is often required for sales promotion

Sales promotion

Sales promotion is one of the four aspects of promotional mix. Media and non-media marketing communication are employed for a pre-determined, limited time to increase consumer demand, stimulate market demand or improve product availability...

s and manufacturer rebate

Rebate (marketing)

A rebate is an amount paid by way of reduction, return, or refund on what has already been paid or contributed. It is a type of sales promotion marketers use primarily as incentives or supplements to product sales. The mail-in rebate is the most common...

s as evidence that the customer purchased the product. When multiple purchases are required to redeem these rewards, it is referred to as a premium incentive or collector mechanic.

Traditional proof of purchase systems required the consumer to send some portion of the packaging, as defined by the product's manufacturer, or the sales invoice.

Unique codes printed on packaging are increasingly used as a mechanism for proof of purchase. Consumers can submit the code electronically for validation against a central database, thus establishing proof of purchase. Such systems allow manufacturers to develop a direct relationship with the consumer, for use in short term sales promotions, loyalty systems and collection and profiling of consumer data.